
METHODS FOR DETERMINING 


DENSITY AND SPECIFIC GRAVITY 


COAL GAS. 


By WILLIAM W. 'GOODWIN, 

Author of the History and Principles Involved iu the Use of Lowe’s Jet Photometer. 


PUBLISHED BY WM. W. GOODWIN & CO., 

GAS METER MANUFACTURERS, 

1012 , 1011 , and 1016 FILBERT STREET , 
PHILADELPHIA, PA. 

1875 . 


WM. WALLACE GOODWIN. 


HOWARD KIRK, SPECIAL PARTNER. 














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'* , 






§ 




METHODS FOR DETERMINING 


THE 


DENSITY AND SPECIFIC GRAVITY 


COAL GAS. 


BY 


WILLIAM W. GOODWIN, 

AUTHOR OF THE HISTORY AND PRINCIPLES INVOLVED IN THE USE OF 

lowe’s jet photometer. 



PUBLISHED BY WILLIAM W. GOODWIN & CO., 

GAS METER MANUFACTURERS, 1012, 1014, AND 1016 FILBERT STREET, 


PHILADELPHIA, PA. 
1875 . 




Wm. Wallace Goodwin. 


Howard Kirk, Special Partner. 





A 



Entered according to Act of Congress, in the year 1875, by 
WM. W. GOODWIN, 

in the Office of the Librarian, at Washington. All rights reserved. 





PHILADELPHIA: 
COLLINS, PRINTER, 

705 Jayne Street. 








DENSITY AND SPECIFIC GRAVITY OF GASES. 


In presenting the following methods for determining the Density and 
Specific Gravity of Coal Gas, the author does not desire to lay claim to 
any new methods for determining the same, but rather to present, in as 
concise a form as possible, consistent with a proper understanding of 
the subject, the principles, and the several methods in use for the pur¬ 
pose, and to call attention to an instrument designed by him for arriving 
at the Density and Gravity of Coal Gas, by what is known as the Effu¬ 
sion Method, the simplicity of which, he feels confident, must recommend 
itself. In compiling the following pages, the author acknowledges his 
indebtedness to 4 Fresenius’s’ and ‘Fowne’s Chemistry,’ ‘Bunsen’s Gaso- 
metry,’ and 4 Sugg’s Gas Manipulations.’ He trusts his efforts may be 
the means of directing the attention of Gas Engineers to the fact that 
the Density and Gravity of Coal Gas have to do with its quality and 
illuminating power. It is an established fact that, if Coal Gas is free 
from carbonic acid and air, specific gravity is a proper test of quality 
as well as an approximate test of its illuminating power, because the 
carbon vapors increase the weight of a given volume on which its light¬ 
giving power depends. 

Numerous experiments led Mr. Clegg to assert that the illuminating 
power is almost directly as the specific gravity, viz., if the specific gravity 
.300 gives six candles, .500 gives the light of ten.* Specific gravities of 
Coal Gas vary from .340 to .600. Carbonic acid and air increase the 
weight, and when present greatly diminish the luminosity of the flames, 
in which case the specific gravity cannot be relied upon. 

* The author does not wish to be understood as asserting the correctness of this 
theory, but only as calling attention to the conclusion arrived at by Mr. Clegg after 
numerous experiments. 



4 


It is of great importance to understand clearly what are meant by 
the terms density and specific gravity- two terms which are constantly 
confounded in the ordinary use of language. By the density of a body , 
is meant its mass , or quantity of matter compared with the mass or 
quantity of matter of an equal volume of some standard body arbitrarily 
chosen. Specific gravity denotes the weight of a body, as compared 
with the weight of an equal bulk or volume of the standard body, which 
is reckoned as unity.* In all cases of solids and liquids the standaid 
of unity adopted in this country is pure water at the temperature of 60° 
Falir. For coal gas air is used as a standard of comparison. These 
articles are taken for the sake of convenience, being always at hand, 
and easily obtained in a state of comparative purity. An ordinary ex¬ 
pression of specific weight, therefore, is a number explaining how many 
times the weight of an equal bulk of water is contained in the weight of 
the substance spoken of. If, for example, we say that concentrated oil of 
vitriol has a specific gravity equal to 1.85, or that perfectly pure alcohol 
has a density of 0.794, we mean that equal bulks of these two liquids, and 
of distilled water, possess weight in the proportion of the numbers 1.85, 
0.794, and 1, at 60° Fahr. It is necessary to be particular about the 
temperature, for liquids are extremely expansible by heat; otherwise a 
constant bulk of the same liquid will not retain a constant weight. 

It requires some little abstraction of mind to realize completely the 
condition in which all things at the surface of the earth exist. We live 
at the bottom of an immense ocean of gaseous matter, which envelops 
everything, and presses upon everything with a force which appears, at 
first sight, perfect^ incredible, but whose actual amount admits of easy 
proof. Gravity being, as far as is known, common to all matter, it is 
natural to expect that gases , being material substances, should be acted 
upon by the earth’s attraction as well as solids and liquids. This is really 
the case, and the result is the weight or pressure of the atmosphere, 

* In other words, density means comparative mass, and specific gravity com¬ 
parative weight. These expressions, although really relating to distinct things, are 
often used quite indifferently in chemical writings, and without practical incon¬ 
venience, since mass and weight are directly proportional to each other. 


5 


which is nothing more than the effect of the attraction of the earth on 
the particles of air. 

In describing the leading phenomena of the atmospheric pressure, it 
is necessary to notice one very remarkable feature in the physical con¬ 
stitution of gases, upon which depends the principle of an extremely 
valuable instrument, the air-pump, viz., gases are in the highest degree 
elastic; the volume or space which a gas occupies depends upon the 
pressure exerted upon it —that is to say, the volume of gas is inversely 
as the pressure ; the density and elastic force are directly as the pressure, 
and inversely as the volume. 

For instance, 100 cubic inches of gas under a pressure of 30 inches of 
mercury, would expand to 200 cubic inches were the pressure reduced 
to one-half, and shrink on the contrary to 50 cubic inches, if the original 
pressure were to be doubled. The change of density must necessarily 
be in the inverse proportion to that of the volume, and the elastic force 
follows the same rule. 

To determine with the utmost degree of accuracy the specific gravity 
of a gas, is an operation of very great practical difficulty, but, at the 
same time, of very great importance. There are several methods which 
may be adopted for the purpose. The one described below requires the 
most scrupulous care, and the observance of a number of minute pre¬ 
cautions which are absolutely indispensable to success. 

The plan of operation is as follows:— 

A large glass globe is to be filled with the gas to be examined, in a 
perfectly pure and dry state, having a known temperature, and an elas¬ 
tic force equal to that of the atmosphere at the time of the experiment. 
The globe so filled is to be weighed, it is then to be exhausted at the 
air-pump as far as possible, and again weighed. Lastly, it is to be filled 
with dry air, the temperature and pressure of which are known, and its 
weight once more determined. On the supposition that the temperature 
and elasticity are the same in both cases, the specific gravity is at once 
obtained by dividing the weight of the gas by that of the air. 

Mr. Sugg, in treating of this subject, describes two processes em¬ 
ployed for determining the specific gravity of a gas : first by means of 
a glass globe. To carry out this experiment accurately, he says that 




a good air-pump is absolutely necessary; a very light globe of hard 
German glass is provided with a stopcock at each end. The capacity 
of this ball is about 100 cubic inches. Having adjusted the balance, 
weigh the globe accurately to the fractional part of a grain, and then 
remove it to the air-pump; exhaust the air, weigh it again, and the 
number of grains and tenths of a grain represents the weight of the air 
abstracted. Suppose it takes 31; now fill the ball with gas from the 
gas-holder, remove it and weigh it again ; and the number of grains re¬ 
presents the weight of the gas introduced. Suppose it takes thirteen; 
then— 

As 31 : 13 :: 1.000 
13 


31 )13.000( .419 Answer . 
12 4 


60 

31 

290 

279 


11 

The specific gravity of the gas is therefore .419, air being taken at 1.000 ; 
and as 100 cubic inches of pure and dry atmospheric air weigh at mean 
temperature and pressure 31.0117 grains, the weight of 100 inches of 
the gas can be easily determined; for— 

As 1.000 : .419 :: 31.0117 
.419 


2791053 

310117 

1240468 


1.000 )12.9939023 


12.9939 Answer. 








7 


That is, the specific gravity of air is to the specific gravity of the gas 
what the weight of 100 inches of air is to the weight of 100 inches of the 
gas, and from this result the weight of any quantity of the gas can of 
course be determined. 

Dr. Letheby’s method of ascertaining the specific gravity of gas is as 
follows: He uses a glass globe of about six inches in diameter, with a 
double neck. The two necks are opposite 
each other, and are fitted with small caps 
and very small stopcocks. One of the stop¬ 
cocks screws into a gas-pillar, and so sup¬ 
ports the globe; the other carries a cap, witli 
a glass tube about one-half an inch in diame¬ 
ter and seven inches long. This tube con¬ 
tains a thermometer, and is fitted at the 
opposite end with a jet for burning the gas. 

(See figure.) The globe with the stopcock 
attached, but without the tube, is accurately 
balanced while in an exhausted state, and a 
counterpoise weight is provided. The exact 
weight of the globe, when full of air at 60° 

Fahr. and thirty inches barometrical press¬ 
ure, is ascertained, and engraved on the 
globe. 

In practice the globe is always attached 
to the gas-pillar, and therefore gas is constantly passing through it, so 
that it is always full of gas ready for weighing. When the specific 
gravity is required, the gas is shut off by first turning the lower stop¬ 
cock, and then a moment after the upper one, so that the globe at the time 
of weighing has not the contained gas at the pressure in the main, but 
at the atmospheric pressure; it is then suspended from the beam of the 
balance, and its exact weight determined. By the simple rule of three the 
specific gravity of the gas is ascertained. For instance, say the weight 
of the globe, when full of air, is sixty grains more than the counter¬ 
poise of the globe in its exhausted state, and that when it is taken from 









8 


the gas-pillar, and is full of gas, the weight of the globe is twenty-five 
grains; then, as 60 : 1.000 (the specific gravity of air) :: 25 : .416 (the 


specific gravity of the gas). 

This example is worked out thus:— 


Weight of the globe 
in grains when 
full of air. 

60 


Standard specific 
gravity of air. 

1.000 


Weight of the globe 
in grains when 
filled with gas. 

25 

1.000 


60)25.000 

.416 Answer. 


Correction is then made for temperature and barometric pressure. 

The advantage of this apparatus is, that it requires no exhausting b}' 
an air-pump, but is always ready for experiment. To operate success¬ 
fully, however, with either form of apparatus described, access to a very 
delicate balance is indispensable. 

The author will now call attention to the Effusion Method. 

The rates of effusion of gases, that is to say, their rates of passage 
through a minute aperture in a thin plate of metal or other substance 
into a vacuum, follow the same law as their rates of diffusion, that is to 
say, they are inversely as the square roots of the densities of the gases. 
Nevertheless, the phenomena of Diffusion and Effusion are essentially 
different in their nature, the effusive movement affecting masses of a gas, 
whereas the diffusive movement affects 011 I 3 ' molecules; and a gas is usu¬ 
ally carried by the former kind of impulse with a velocity man}’ thousand 
times greater than by the latter. Mixed gases are effused at the same 
rate as one gas of the actual density of the mixture ; and no separation 
of the gases occurs, as in diffusion into a vacuum. 

The law of effusion just stated is true only under the condition that 
the gas shall pass through a minute aperture in a very thin plate. If 
the plate be thicker, so that the aperture becomes a tube, veiy different 
rates of efflux are observed ; and when the capillary tube becomes con¬ 
siderably elongated, so that its length exceeds its diameter at least four 





9 


hundred times, the rates of flow of different gases into a vacuum again 
assume a constant ratio to each other, following, however, a law totally 
distinct from that of effusion. The principal general results observed, 
with relation to this phenomenon of u Capillary Transpiration,” are as 
follows:— 

1st. The rate of transpiration of the same gas increases, other things 
being equal, directly as the pressure; that is to sa 3 T , equal volumes of 
gas, at different densities, require times inversely proportional to their 
densities. 

2 d. With tubes of equal diameter, the volume transpired in equal 
times is inversely as the length of the tube. 

3d. As the temperature rises, the transpiration of equal volumes be¬ 
comes slower. 

4th. The rates of transpiration of different gases bear a constant rela¬ 
tion to each other, totally independent of their densities, or indeed of 
any known property of the gases. Equal weights of oxygen, nitrogen, 
and carbon monoxide* are transpired in equal times; so likewise are equal 
weights of nitrogen, nitrogen dioxide,* and carbon monoxide ; and of 
hydrogen, chloride, carbon dioxide,* and nitrogen monoxide. In other 
words, this method is based on the fact that the specific gravity of tw T o 
gases which stream out of a fine opening in a thin plate, are very nearly 
proportional to the square of the time of effusion. If a gas of specific 
gravity S requires the time f, and another gas of specific gravity S, 
requires the time the relation between the times of effusion and the 

S t 3 

specific gravities is represented by the equation -_!•=-L. If $, or the spe- 

o t l 

cific gravity of one gas, be made equal to 1 , the specific gravity of the 

* Composition. 


By weight. By volume. 



Carbon. 

Oxygen. 

Carbon. 

Oxygen. 

Carbon monoxide [i. e carbonic oxide] . . 

. . 12 

16 

1 

1 

Carbon dioxide [i. e., carbonic acid] . . . 

. . 12 

Nitrogen. 

32 

1 

Nitrogen. 

2 

Nitrogen monoxide [i. e. , nitrous oxide] . . 

. . 28 

16 

2 

1 

Nitrogen dioxide [i. e., nitric oxide] . . . 

. . 28 

32 

• 2 

2 






10 


/ 3 

other is found from the formula S. = —. Thus, it will be seen that by 

1 t* 

means of this method the time of effusion of a column of gas is obtained 
having a constant length on a tube, and issuing under pressures the 
sum of which remains always constant. This time of effusion, deter¬ 
mined for various gases, raised to the square, gives the relation of the 
specific gravities of the gases. The following experiments show the 
degree of accuracy which can be attained by this method. The first 
column t contains the times of effusion of a volume of air; the second 
column the times of effusion of an equal volume of gas; the third and 
fourth columns the square of these observed times; and the fifth column 
the specific gravities calculated from these squares. 


Air. 

t. 

Hydrogen. 

h 

t\ 

*, 2 . 

t? 

7 2 

105.5 

29.7 

11130 

882.09 

0.0792 

105.0 

30.0 

11025 

900.10 

0.0816 

105.5 

29.5 

11130 

870.25 

0.0782 

105.0 

29.3 

11151 

858.49 

0.0770 

105.5 


11130 




The mean specific gravities, calculated from a number of experiments, 
are collected in the following table. The first column contains the expe¬ 
rimental results; the second column the same values calculated from 
atomic weights. 


Gases. 

I. 

II. 

Difference. 

Air..... 

1.000 

1.000 


Carbonic acid ........ .. . 

1.535 

1.520 

+0.015 

1 Vol.CO+1 vol. CO*.. 

1.203 

1.244 

—0.041 

Oxygen... 

1.118 

1.106 

+0.012 

Electricity deton. gas ... 

0.414 

j 0.415 

—0.001 

Hydrogen ...... 

0.079 

0.069 

+0.010 
































11 


It is seen that the agreement between the experimental, and the calcu¬ 
lated values, is very close. For technical purposes, as lor instance, the 
determination of the specific gravity of coal gas, this method is peculiarly 
applicable from its extreme simplicity. The author has designed a form 
of apparatus, based upon the foregoing 
method, the object of which is to simplify 
and render less costly, without diminishing 
materially the accuracy of, the apparatus 
for taking the density or specific gravity 
of coal and other gases, by the efflux of the 
same through a fine opening in a thin plate 
of metal. The figure exhibits the apparatus. 
a is a glass jar or water-holder; b is a glass 
tube divided into a number of equal parts 
for measuring gas; c is a movable cap; d is 
a stopcock attached to tube b ; e is the top, 
containing the orifice for the effusion of 
gas; f rubber hose attached to tube b. 

The apparatus is prepared for operation 
by detaching and withdrawing the tube b, 
and pouring water into the vessel a, in suf¬ 
ficient quantity to bring its surface up to 
about, or a little above, the upper line of 
the glass tube b ; on introducing the latter, 
and securing it by the catch, the stopcock 
d being at the same time closed, the air in 
the tube b will be confined therein. 

The apparatus being thus made ready, 
the operator, with stop-watch in hand, opens the stopcock d. The air 
in b slowly escapes through the minute orifice in the metal plate on the 
top of the tip e ; when the rising water reaches the number 1 line on 
the glass tube b, he starts his stop-watch, and carefully observing the 
rising water, stops his watch the instant the surface line of the water 












12 


reaches, sa} r , the highest number 10, and notes the time occupied by the 
effluxion of the nine inches of air. 

The operator now detaches the tip e, and inserts the end of stopcock 
d Into the end of a rubber tube e, and passes a current of the gas to be 
tested, down through b until the atmospheric air is driven out, and its 
place occupied by the gas only, then closes the stopcock D, detaches the 
rubber hose, and reinserts the tip e as before. Now, with his stop-watch 
in hand, he opens the stopcock and starts his watch the instant the sur¬ 
face line of the water in b reaches 1, and carefully observing the rising 
water, stops his watch the instant the surface line of the water reaches 
the line numbered 10, and notes the time occupied by the effluxion of 
the nine inches of gas. He now squares the time required for each of 
the fluids to pass through the orifice, and divides the square of the gas 
by the square of the air. The result is the density or specific gravity of 
the gas. 

For example, suppose the time of effusion of air equalled 139 seconds, 

t 3 

and for gas 90 seconds, then, according to the formula given, S x = ; the 

{ 


specific gravity of the gas is found by dividing the square of the time of 
effusion of the gas by the square of the time of effusion of the air, thus 

(jro a ti mp 3 

% - ; —- = specific gravitv of the gas. 

air time 2 * & 

The air flowed through the orifice in 139 seconds. Gas flowed out in 

90 seconds, therefore— 


Gas time 3 
Air time 3 


90 2 
139 2 


.419. 


Square of Square of 
air time, gas time. 


19321)8100.0(.419 
77284 


specific gravity. 


37160 

19321 


178390 

173889 





13 


1 lie instrument should be read from lowest part or curve of the water, 
called the meniscus . Its accuracy may be shown with either olefiant or 
hydrogen gases, the true specific 
gravity of olefiant gas being 0.981, 
and that of pure hydrogen 0.0695. 

The tip should be covered when not 
in use, as dust soon clogs it if left 
exposed. 

The Fig. represents a stop-watch 
which is furnished with the instru¬ 
ment when desired, and is so con¬ 
structed that, after starting the 
timer by placing the finger on the 
button a, the hands instantly re¬ 
turn to zero, and remain in that 
position until the finger is removed. 

The timers are also useful for pho- 
tometrical and burner tests. Each is warranted, and furnished in a 
small velvet-lined box. Annexed are tables of squares from 50 to 200 
seconds, which can be used in the tests. 


Seconds. 

Squares. 

Seconds. 

Squares. 

Seconds. 

Squares. 

50 ... . 

25 00 

62 .... 

38 44 

74 .... 

54 76 

51_ 

26 01 

63 .... 

39 69 

75 .... 

56 25 

52 .... 

27 04 

64 .... 

40 96 

76 .... 

57 76 

53 .... 

28 09 

65 .... 

42 25 

77 .... 

59 29 

54 .... 

29 16 

66 .... 

43 56 

78 .... 

60 84 

55 .... 

30 25 

67 .... 

44 89 

79 .... 

62 41 

56 .... 

31 36 

68 .... 

46 24 

80 .... 

64 00 

57 .... 

32 49 

69 .... 

47 61 

81 .... 

65 61 

58 .... 

33 64 

70 .... 

49 00 

82 .... 

67 24 

59 .... 

34 81 

71 .... 

50 41 

83 ... . 

68 89 

60 .... 

36 00 

72 .... 

51 84 

84 ... . 

70 56 

61 .... 

37 21 

73 .... 

53 29 

85 .... 

72 25 












14 


Seconds. 


Squares. 

Seconds. 

Squares. 

Seconds. 

Squares. 

86 .... 


73 

96 

119 

1 

41 

61 

152 .... 

2 

SI 

04 

87 .... 


75 

69 

120 .... 

1 

44 

00 

153 .... 

2 

34 

09 

88 .... 


77 

44 

121 .... 

1 

46 

41 

154 .... 

2 

37 

16 

89 


79 

21 

122 

1 

48 

34 

155 

2 

40 

25 

90 .... 


81 

00 

123 .... 

1 

51 

29 

156 .... 

2 

43 

36 

91 


82 

81 

124 

1 

53 

76 

157 

‘2 

46 

49 

92 .... 


84 

64 

125 

1 

56 

25 

158 .... 

2 

49 

64 

93 .... 


86 

49. 

126 .... 

1 

58 

76 

159 

2 

52 

81 

94 


88 

36 

127 

1 

61 

29 

160 .... 

2 

56 

00 

95 .... 


90 

25 

128 .... 

1 

63 

84 

161 .... 

2 

59 

21 

96 .... 


92 

16 

129 .... 

1 

66 

41 

162 .... 

2 

62 

44 

97 .... 


94 

09 

130 .... 

1 

69 

00 

163 

2 

65 

69 

98 .... 


96 

04 

131 

1 

71 

61 

164 

2 

68 

96 

99 .... 


98 

08 

132 

1 

74 

24 

165 .... 

2 

72 

25 

100 

1 

00 

00 

133 .... 

1 

76 

89 

166 

2 

75 

56 

101 .... 

1 

02 

01 

134 .... 

1 

79 

56 

167 .... 

2 

78 

89 

102 ... . 

1 

04 

04 

135 .... 

1 

82 

25 

168 

2 

82 

24 

103 

1 

06 

09 

136 .... 

1 

84 

96 

169 

2 

85 

61 

104 .... 

1 

08 

16 

137 .... 

1 

87 

69 

170 .... 

2 

89 

00 

105 

1 

10 

25 

138 .... 

1 

90 

44 

171 .... 

2 

92 

41 

106 .... 

1 

12 

36 

139 

1 

93 

21 

172 .... 

2 

95 

84 

107 .... 

1 

14 

49 

140 

1 

96 

00 

173 .... 

2 

99 

29 

108 .... 

1 

16 

64 

141 .... 

l 

98 

81 

174 .... 

3 

02 

76 

109 .... 

1 

18 

11 

142 .... 

2 

01 

64 

175 .... 

3 

06 

25 

110 ... . 

1 

21 

00 

143 

2 

04 

49 

176 .... 

3 

09 

76 

Ill .... 

1 

23 

21 

144 

2 

07 

36 

177 

3 

13 

29 

112 .... 

1 

25 

44 

145 .... 

2 

10 

25 

178 .... 

3 

16 

84 

113 .... 

1 

27 

69 

146 .... 

2 

13 

16 

179 

3 

20 

41 

114 .... 

1 

29 

96 

147 .... 

2 

16 

09 

180 .... 

3 

24 

00 

115 .... 

1 

32 

25 

148 .... 

2 

19 

04 

181 

3 

27 

61 

116 .... 

1 

34 

56 

149 .... 

2 

22 

01 

182 .... 

3 

31 

24 

117 .... 

1 

36 

89 

150 .... 

2 

25 

00 

183 .... 

3 

34 

86 

118 .... 

1 

39 

24 

151 .... 

2 

28 

01 

184 .... 

3 

38 

56 










15 


Secon's. 

Squares. 

Seconds. 

Squares. 

Seconds. 

Squares. 

185 

. 3 42 25 

191 .. 

.. 3 64 81 

196 ... 

. 3 84 16 

186 

. 3 45 96 

192 . . 

. . 3 68 64 

197 ... 

. 3 88 09 

187 ... 

. 3 49 69 

193 . . 

. . 3 72 49 

198 ... 

. 3 92 04 

188 ... 

. 3 53 44 

194 . . 

. . 3 76 36 

199 ... 

. 3 96 01 

189 .. . 

. 3 57 21 

195 . . 


200 ... 

. 4 00 00 

190 .. . 

. 3 61 00 






TABLE. 

(Newbigging ? s.) 

Comparing the Specific Gravity of Gas (air being 1.000) with the Illu¬ 
minating Power in Standard Sperm Candles—assuming that the Gas 


is pure. 

No. of 

Candles. 

10 equal to about . , 

Specific 

Gravity. 

.. . .380 

No. of 

Candles. 

24 equal to about . 

Specific 

Gravity. 

.. . .565 

11 “ 

tt 


25 

tt 

tt 

... .585 

12 “ 

tt 

. . . .405 

26 

tt 

tt 

.. . .605 

13 “ 

tt 

. . . .406 

27 

tt 

tt 

... .625 

14 “ 

tt 

.. . .430 

28 

tt 

tt 


15 “ 

tt 

. . . .443 

29 

;t 

tt 

.. . .662 

16 “ 

tt 

. . . .455 

30 

tt 

it 

.. . .678 

17 “ 

tt 

. . . .468 

31 

;t 

tt 

.. . .694 

18 “ 

tt 

. . . .482 

32 

tt 

tt 

oo 

o 

I— 

19 “ 

tt 

. . . .495 

33 

tt 

tt 

... .722 

20 “ 

tt 

... .508 

34 

tt 

.t 

oo 

CO 

1— 

21 “ 

tt 

. . . .522 

35 

tt 

tt 

... .755 

22 u . 

tt 

... .537 

36 

tt 

tt 

... .775 

23 “ 

tt 

... .550 

37 

tt 

tt 

... .790 






























WM. AV. GOODWIN & CO., 


1012, 1014, and 1016 Filbert Street, Philadelphia, 

MANUFACTURERS OF 

WET AND DRY GAS METERS, STATION METERS 
(Square, Cylindrical, or in Staves), TEST 
AND SHOW METERS: 

PRESSURE REGISTERS, VACUUM AND PRESSURE REGISTERS, PRESSURE 
GAUGES, TEST GAS-HOLDERS, ALL SIZES, STANDARD CUBIC 
FOOT MEASURES, STATIONARY OR PORTABLE. 

All kinds of Apparatus for determining quantity of Sulphur and 
Ammonia in Coal Gas by Volumetric Analysis, Eudiometers, and 
Absorption Tubes. Also, all other Testing and Chemical Appa¬ 
ratus, of the most perfect description, relating to gas. 

Photometrical Apparatus of every description. 

Goodwin’s Improved Bunsen, Letheby Electrical Photom¬ 
eter. —This instrument extinguishes the gas and candle, stops the 
meter and clock at any moment desired, either by time, gas, or 
candle. Patented Dec. 22, 1874. 

Goodwin’s Improved Lowe’s Jet Photometer. —This instru¬ 
ment shows the candle power and pressure required for same on 
dial. Patented April 22, 1873; re-issued Jan. 26, 1875. All other 
candle power dials are infringements. 

Goodwin’s Electrical Photometer Balance for weighing can¬ 
dles in sM. Patented Jan. 12, 1875. 

Goodwin’s Density and Specific Gravity Apparatus for de¬ 
terminations by the Effusion Method. Patented Dec. 15, 1874. 

















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